The brutal gang violence in Juárez, Mexico, has been covered thoroughly by the American news media. What has not been as widely reported is the gender-based violence there.

Hundreds of women and girls have been abducted and killed in Juárez since the early 1990s. Their bodies have been discovered in mass graves in the desert outside the city, which is dotted with pink crosses - the symbol of the missing women of Juárez. The remains show the victims were battered, sexually abused, and at times grotesquely mutilated, leaving their identities unknown. It's an extremely alarming case of mass violence against women.

This and other cases of gender-based violence are the subject of the powerful art exhibition "Ni una mas (Not One More): The Juárez Murders" at Drexel University's Leonard Pearlstein Gallery through July 16.

For every victim, there is a murderer. Who are these anonymous agents of violence? What motivates them? And why aren't the community, the Mexican government, and the factories that employ the women doing more to protect them?

Many of the murdered women are never found, compounding the psychological assault on their loved ones. This lack of closure associated with the community's complete failure to account for its own is one of the most disturbing aspects of the missing women of Juárez.

Most of the victims are poor factory workers - some as young as 12 years old - exploited by multinational corporations for minimal wages. A related problem, and a backdrop of the femicide, is that seven of 10 Mexican women have been victims of domestic abuse.

Genocides have a pattern. Whether it's the Holocaust, Yugoslavia, Rwanda, or Juárez, the community permits the crimes. Although some members of the Juárez community have shown courage, there is an absence of widespread outrage.

Very few of the Juárez killers are caught and prosecuted, and little is known about them. It would be comforting to think of them as different, unusual, sick. But the ordinary, routine nature of the killings makes them even more chilling.

The twin border cities of Juárez, Mexico, and El Paso, Texas, are geographically contiguous, but in many ways they could not be farther apart. Bystanders, an essential ingredient in any terrorist movement, enable the calamity to continue. Are we all bystanders?

The tragic truth is that Juárez is the ideal place to kill a woman, because one is almost certain to get away with it. The murders are the result of history, psychology, and culture culminating in a quest for power in the form of sexual violence against women. But a femicide is not possible without bystanders who look the other way. This is terrorism that we can see over our backyard fence.

Eric A. Zillmer is a professor of neuropsychology and director of athletics at Drexel University. For more information on the exhibition, see www.drexel.edu/juarez.